Portable X-ray or gamma source



July 2, Y 1957 s. UNTERMYER 2,798,164

PORTABLE x-RAY 0R GAMMA SOURCE Filed April 2o, 1954 ATTORNEY UnitedStates Patent PoRrALE x-RAY on GAMMA sonnen Samuel Uiltermyer,4 DownersGrove, Ill., assigner to .the United States of Americaas'represented bythe United States'Atomic Energy Commission Application April 20, 1954,SerialNo. 424,536A

3 Claims. (Cl. Z50-10,6)

This invention relates,` to, a source lof radioactivity, and moreparticularly, to a. radioactive source that is compact and portable;l

y The need isgreat, for aradioactive source` that can be carried byhandv from place to place; Aportable source of radioactivity could haveconsiderablel usey by Army surgeons for emergency X-ray photography-Vaud. fluoroscopy at advanced: bases Orrin the feld where: use of apermanent' X-ray;` apparatus is impossible. When the portable sourceemits; gamma rays, there, willl be con- Sider-able; use, iu. industrial;plants for testing purposes.

'Obit-1ct." of: the: present` inventionV is: toy provide a sourceV offradioativity that is' compact and can readily becarriedr by; hand; Ihave been; able to: accomplish this by designingl the radioactivesource. so that the,- projection: off i'tsactivi-ty can b 'e controlledwithout the. use; of a; shutter; whichA I haver foundt must: be; verylarge4` in orderr not; to. limit; the. useful solid angle of. emissionof radiation. AA large;l shutter interferes with portability.

Other objects. will become apparent from the.V drawing anddescriptio-rrthatfollows.

In. the; drawing z;

. Fig.,` lis a sectional: view4 taken throughf the n'ovel radioactive,source` oi: the. present invention;-

Fig?. 2:is'.a sectionalfview taken through' theradioactive capsule.employed inithe; above source; and.

FigaA 3. is` a sectional View taken through atportion` of the releasingmechanism for the capsule;

The device;V thatfconstitutes: a radioactive; source` comprises.essentially a'. radioactive. capsule 10:, a shielding body 11 having; a=crooked't or. curved passa-ge, andia wire rod 12 for moving the capsule`10 between:` an: operative position shown in dotted lines in Fig. l andau inoperative or inactiveA position shownin full-lines; in Fig. l.

The capsule libicomprises an active corea 13 and a casingformed. of acup 14 and pluglS. which completely enclose, thecore 1'3. The core isformed-of a radioactive material, which emits radiation, of. the.desired.` energy. Thulium--170, which emits 52 k. e. v.,X'-rays, andamericium-2l42g1whicli emits 40 k. e. v. gamma raysn are-.suitablesources for radiographic purposes, while cobalt-60 is a suitable sourceof 1.6 m. e. v. gamma rays for radio- 'graphic purposes and also fortherapeutic purposes. The thulium can be a mixture of thulium-169 andthulium- 170, which may be formed by the irradiation of thulium- 169 ina neutronic reactor. The material of the core may be in the form of ametal disk, a compound of the metal, or an enclosure containing powderof the metal or a compound of the metal. lf the core 13 is a disk ofmetallic thulium, it may be .16 in. in diameter and .070 in thickness.The dimensions listed for the parts about to be described are suitablewhen the core 13 is thulium or americium. Much larger dimensions arerequired if the core is cobalt. The cap 14 and plug 15 should be of acorrosion-resistant that does not emit undesirable radiation, such asaluminum. The cup 14 should be .375 in. in length, .050 in. in basethickness, .22 in. in outer diameter, and .16 in. in inner diameter.

The base of the aluminum cap 14 serves to lter out undesirable betaradiation from the thulium. The aluminum plug 15 should be .255 in. inlength and .16 in. in outside diameter. There should be an annular bond16 formed between the ends of the cup 14 and the plug 15 to seal thecore 13 within the cup aud the plug.

A fastening member 17, which is secured in a threaded connection to theplug 1S, attaches one end of the wire rod 12 to the capsule I0. Thefastening member 17 and the wirev rod 12 may be formed ofk stainlesssteel and are attached to one another as by bonding.

The body 11 is preferably formed of lead and has a lengthv of 4.19 in.and'a diameter of 1.87 in. The' crooked curved passagev thereinmounting'the radioactive capsule 10 is formed by' a stainless-steel tube1Sl which is embedded in the body 1'11 and extends from the neighborhoodof one end face 19 ofA the body through the body almost to an oppositeend face 20. The internal diameter of the. tube 18. is` .25 in., so thatthe capsule 1i), which has an external diameter ofA .22 in., Ihas aloose sliding t therein. The tube 1S is curved in a single plane or isspiral so that when the capsule 10l lies against the. end of astainless-steel bushing 20a located in one end of the tube 18, that is,lies in the inactive position shown in full lines in Fig. 1, there is noline of sight to the. capsule 10 through the body from end face 19, andso emanations from the capsule 1d cannot get out at this end face. Therelatively close fit of' the wire rod 12' in the bushing Ztla preventsescape lof emanations from the capsule at end face 20. The opening inthe bushing 20a may be .0625 in. in diameter, and the wire rod 12, .0458in. in diameter. The bushing 20a is about 'one inch long so that'in theinactive position of the capsule. 10 about oneinch of shieldingA body1-1 liesbetween the endVV face 20v of thel body andthe capsule. Yetthelateral displacement 'of the intermediate portion of the tube 18should not" be so much as to reduce the minimum thickness of the body1'1" at the intermediate portion of the tube 18 to the extent thatemanations from the capsule y can escape radially through the body 11.

The endv of the stainless-steel'tube 18 adjacent the end face 19 of thebody 11i is at the small end of a conical recess that has a solidY angleIof about and is formed of? a conical" recess 21 in the body 121 havinga diameter of' .26 in. at it-s small end and a conical hole 22 formed ina stainless-steel plate. 23. The outer diameter of the tube 18 is also.26 in., and this is the same size as the smally end' of the recess 21.The depth of thel conical reces 21 is .19 in. The plate 23', which is.125 in; thick, ser-ves tohold againstend face 19 of body 1'1, a plasticplate 2dof .03 in. thickness formedV of methyl methacrylate. Theplate 24shields the `body 11 againstl the entrance `of foreignl material such asdust at the recess 21. Thepla-te 23n is secured to thebody 11' by threescrews 25` spaced about 120 from one another about the conical recess22. The end face 20 `of the body 11 is covered by a plate 26 which is.125 in. thick and is secured thereto by three screws 27 spaced about120 from one another about the tube 18. The bushing 20a has an endflange 27a by which the bushing is clamped in a recess in the end face20 of the body 11 by the plate 26. The body 11 is encased in acylindrical sheath 28 fof stainless steel, which may be suitably bondedto the plates 23 and 26.

The wire rod 12 projects considerably beyond the protruding end of thetube 18 and has at its end remote from the capsule 10 a button 29, whichmay be of stainless steel. A flexible hose or tube 30, which may be ofwoven metal wire or cloth or both or of spirally wound wire, containsthe wire rod 12 and has one end secured within a tubular ange 30a formedon the end plate 26 and a perforated metal disk 31 secured to its otherend. The

rod 12 passes through the which surrounds a portion of the rod 12 andlies within the hose 30 has one end secured to the disk 31 and the otherend secured to the rod 12 and serves yieldingly to hold the capsule inits inactive position and the button 29 spaced from the disk 31, both asshown in full lines in Fig. 1.

The spacing of the button 29 in its full-line position from theperforated disk 31 is about equal to the distance between the inactivefull-line position of the capsule 10 and the active dotted-line positionthereof, so that depression of the button 29 to the perforated disk 31causes the capsule 10 to move from inactive position to active disk 31.A coil `spring 32 position. Engagement of the button 29A with the diskthereby. Release of the button 29 permits the capsule 5 10 to bereturned to its inactive full-line position through the action of spring32. Depression yof the button 29 to the disk 31 may be accomplished byengagement of the button 29 by the thumb and of the disk 31by the indexand middle fingers of the same hand, the disk 31 protruding radiallyoutwardly beyond the tube 30 to make the latter engagement possible.

The significant thing about the device of the present invention is thatthe active capsule 10 moves from an exposed active position at one endof the shielding body 11 to an inactive position deep within theshielding body and that shifting of the active capsule between thesepositions is carried out manually by means of the wire rod 12 and thespring 32. This arrangement dispenses with the need for shutters orother movable closure elements at the end `where the capsule liesexposed in its active position. Thus there are no moving parts where theactive capsule is exposed, the construction is simple and compact, andthe over-al1 dimensions are held to a minimum. It is t0 be noted thatcapsule 10 in its active position gives 01T radiation through a wideangle, about 120, as shown. A rotary shutter at the outside of the plate23 would have to be quite large in order to handle the wide angle ofradiation. The large shutter would make associated parts large and thelarge over-all size would interfere with portability. Itis alsosignificant that the tube 18 in which the capsule 10 is moved betweenactive and inactive positions is curved in such a way that, when thecapsule is in its inactive position, there is no line of sight to thecapsule through the end of the tube 18 adjacent the cover 24, andemanations cannot escape through this end of the tube. Emanations cannotescape from the other end of tube 18, because of the relatively closefit of the wire rod 12 in the tubular section 20a.

The intention is to limit the invention only within the scope of theappended claims.

What is claimed is:

1. An assembly comprising a body of shielding material having a curvedpassage extending therethrough between first and second opposite ends ofthe body, a capsule con- 4 taining radioactive material and beingslidably mounted in the passage for movement between an active positionin which it is adjacent said first end of the body and can project itsactivity through such first end and an inactive position in which itlies between and spaced from said first and second ends while beingnearer the second end and is capable of projecting its activity throughneither of said ends, a rod connected to the capsule and extendingtherefrom through the passage and out said second end of the body, abushing mounted in the end of the tube adjacent the second end of thebody and fitting the rod relatively closely, a iiexible tube attached tosaid second end of the body and housing the portion ofthe rod exteriorof said second end of the body While leaving the end of said exteriorrod position exposed for manipulation, and resilient means actingbetween the rod and the end of the flexible tube beyond which the rodlies exposed whereby l. the capsule is urged to its inactive position.

2. The assembly specified in claim 1, the end of the curved passage atsaid' first end of the body being conical, the assembly furthercomprising a plastic plate covering said first end of the body and theconical end of the curved passage to retain the capsule in the body, anda retaining plate holding the plastic plate against the body and havinga conical opening formed as a continuation of the conical end of thecurved passage in the body.

3. An assembly comprising a lead body having a curved passage extendingtherethrough between first and second opposite faces, a curvedstainless-steel tube conforming to the passage throughout its length, acapsule having a radioactive core and an aluminum casing completelyenclosing the core, the core being formed of a material emitting gammarays having an energy of at least 40 k. e. v., said capsule beingslidably mounted in the passage for movement between an active positionin which it is adjacent said first end of the body and can project itsactivity through said first end and an inactive position in which itlies between and spaced from said first and second ends but nearer thesecond end and is capable of projecting its activity through neither ofsaid ends, a rod connected to the capsule casing and extending therefromthrough the stainless-steel tube and out of the end of the tube beyondsaid second face of the body, a bushing mounted in the -tube adjacentthe second face of the body and fitting the 45 rod relatively closely, aexible tube having one end connected to the second face of the body andcontaining the rod, the rod projecting beyond the other end of theexible tube, and a spring acting between the rod and said other end ofthe flexible tube for acting through the rod to urge the capsule to itsinactive position.

References Cited in the file of this patent UNITED STATES PATENTS2,412,174 Rhoades Dec. 3, 1946 2,551,491 Gilks May 1, 1951 2,622,209Hjulian et al. Dec. 16, 1952 2,719,823 Zinn Oct. 4, 1955 2,750,517 BaumJune 12, 1956

1.AN ASSEMBLY COMPRISING A BODY OF SHIELDING MATERIAL HAVING A CURVEDPASSAGE EXTENDING THERETHROUGH BETWEEN FIRST AND SECOND OPPOSITE ENDS OFTHE BODY, A CAPSULE CONTAINING RADIOACTIVE MATERIAL AND BEING SLIDABLYMOUNTED IN THE PASSAGE FOR MOVEMENT BETWEEN AN ACTIVE POSITION IN WHICHIT IS ADJACENT SAID FIRST END OF THE BODY AND CAN PROJECT ITS ACTIVITYTHROUGH SUCH FIRST END AND AN INACTIVE POSITION IN WHICH IT LIES BETWEENAND SPACED FROM SAID FIRST AND SECOND ENDS WHILE BEING NEARER THE SECONDEND AND IS CAPABLE OF PROJECTING ITS ACTIVITY THROUGH NEITHER OF SAIDENDS, A ROD CONNECTED TO THE CAPSULE AND EXTENDING THEREFROM THROUGH THEPASSAGE AND OUT SAID SECOND END OF THE BODY, A BUSHING MOUNTED IN THEEND OF THE TUBE ADJACENT THE SECOND END OF THE BODY A ND FITTING THE RODRELATIVELY CLOSELY, A FLEXIBLE TUBE ATTACHED TO SAID SECOND ENDND OF THEBODY AND HOUSING THE PORTION OF THE ROD EXTERIOR OF SAID SECOND END OFTHE BODY WHILE LEAVING THE END OF SAID EXTERIOR ROD POSITION EXPOSED FORMANIPULATION, AND RESILIENT MEANS ACTING BETWEEN THE ROD AND THE END OFTHEE FLEXIBLE TUBE BEYOND WHICH THE ROD LIES EXPOSED WHEREBY THE CAPSULEIS URGED TO ITS INACTIVE POSITION.